Image Sensor Actuator Control for Ripple Current Noise
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Solution Overview
Problem
Image pickup apparatuses using electromagnetic actuators, such as voice coil motors, suffer from image quality deterioration due to magnetic noise, which existing noise suppression methods either require high power consumption or fail to adequately reduce noise.
Innovation Solution
An image pickup apparatus that switches between two energization methods for the actuator, using a first method with higher response distortion and smaller ripple current during charge accumulation and a second method with lower ripple current during signal readout, to minimize noise while maintaining high image stabilization performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the first energization method is used during charge accumulation, then image stabilization performance is improved, but ripple current increases causing noise
Solution Approach 1:
The patent dynamically switches between two different energization methods based on the operational state of the image sensor. During charge accumulation, the first energization method is used to optimize image stabilization performance. During signal readout, the second energization method is used to minimize ripple current and reduce noise in the captured image. This dynamic adaptation resolves the contradiction by applying different control strategies at different times.
Solution Approach 2:
The patent implements periodic switching between energization methods synchronized with the image sensor's operational cycles. The controller alternates between the first energization method (for stabilization performance) during charge accumulation and the second energization method (for noise reduction) during signal readout. This periodic action ensures that each energization method is applied at the optimal moment in the operational cycle.
2Object-generated harmful factors
If the second energization method is used during signal readout, then noise is reduced, but response distortion increases
Solution Approach 1:
The patent dynamically adjusts the energization method based on the real-time operational state of the image sensor. During signal readout, when noise reduction is critical, the second energization method is applied despite its higher response distortion. During charge accumulation, when stabilization performance is paramount, the first energization method is used. This dynamic switching resolves the contradiction by prioritizing different parameters at different operational phases.
Solution Approach 2:
The controller implements periodic switching between energization methods that aligns with the image sensor's charge accumulation and signal readout cycles. The second energization method (with lower ripple current) is applied periodically during signal readout to reduce noise, while the first energization method is applied periodically during charge accumulation to maintain stabilization performance. This periodic action pattern resolves the contradiction between noise reduction and response distortion.
3Object-generated harmful factors
If analog control is used for image stabilization, then noise generation is suppressed, but power consumption increases
Solution Approach 1:
The patent implements periodic switching between analog control (first energization method) and digital control (second energization method) based on the image sensor's operational state. Analog control is applied periodically during charge accumulation when noise suppression is less critical than stabilization performance. Digital control is applied periodically during signal readout when noise reduction is paramount. This periodic switching resolves the contradiction between noise suppression and power consumption by using each control method only when its benefits are most needed.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces noise in images while maintaining high image stabilization performance and minimizing power consumption, thereby improving overall image quality.
Implementation Method 1
Since this type of image pickup apparatus moves an image sensor using an electromagnetic actuator, such as a voice coil motor (VCM)
Data Source
AI summary
An image pickup apparatus includes an image sensor configured to capture an object image, and a controller by controlling energizing an actuator for an image stabilization operation that moves the image sensor. The controller switches an energization method for the actuator between a first energization method and a second energization method that has a response distortion of an actuator larger and a ripple current smaller than those of the first energization method, controls energizing the actuator by the first energization method in a first state that does not read a signal out of the image sensor during a charge accumulation of the image sensor, and controls energizing the actuator by the second energization method in a second state that reads the signal out of the image sensor after the charge accumulation.